使用JPA处理集合更新 [英] Handling collection updates with JPA

问题描述

我有一个自定义对象集合，我想使用JPA以最简单的方式持久化。
我的 CustomObject 类映射到一个表。现在我想知道JPA是否提供某种设施来处理对象集合。

I have a collection of custom objects and I'd like to persist it in the easiest way using JPA. My CustomObject class is mapped to a table. Now I'm wondering if JPA provides some kind of facility to handle object collection.

特别是我想添加或删除对象到我的集合，然后传递给a save（Collection< CustomObject> cco）方法，而不检查哪些对象被更改，我必须添加和删除...

In particular i'd like to add or remove objects to my collection and then pass to a save(Collection<CustomObject> cco) method without checking which object are changed, which I have to add and which to remove...

是否可能？

推荐答案

如果你正在寻找 EntityManager ，这将保存或更新集合，答案是否定的。您必须循环并执行保存或更新。

If you are looking for something in EntityManager which will save or update a collection, the answer is no. You will have to loop and do a save or update.

如果您使用 EntityManager.merge（） API将更新，如果记录已存在或将插入一个新记录。

If you use EntityManager.merge() API it will update if record is existing or else will insert a new record.

就删除而言，JPA或任何其他ORM如何确定要删除该实例，如果它的软删除，列如 is_active 到 true / false ，那么yes通过调用merge可以完成，但如果你想要一个硬删除然后JPA将无法自己确定，您将必须手动进行。

As far as delete is concerned, how will JPA or any other ORM determine that you want to delete that instance, if its a soft delete like updating a column like is_active to true/false, then yes by calling merge it can be done, but if you want a hard delete then JPA won't be able to determine by itself, you will have to do it manually.

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